Question

Use quadratic regression to find

the equation of the parabola
going through these 3 points.
(1,-12), (2,-7), (5,80)
y = [ ? ]x2 + [ ]x + [ ]

Answer 1

y = 6x² -13x -5

Explanation:

(1,-12) (2,-7) (5,80)

y = ax² + bx + c

-12 = a*1² + b*1 + c = a+b+c (1)

-7 = 4a + 2b + c (2)

80 = 25a + 5b + c (3)

(2)-(1): 3a + b = 5 (4)

(3)-(2): 21a + 3b = 87 (5)

(4)*3: 9a + 3b = 15 (6)

(5)-(6): 12a = 72 a = 6

(4) b = -13

(2) c = -5